Touch-enabled devices allow a user to interface with a computer by touching certain areas of a display screen or other surface and are increasing in demand as more users seek intuitive, easy-to-use interfaces. Such devices may use multiple and simultaneous touches to initiate certain computer events, but existing detection systems may have difficulty detecting the more complex combinations of touches.
For example, an optical position detection system may use one or more optical sensors to register touch locations based on imaging a detection area. A touch point corresponding to a first object can become lost or hidden from the view of optical sensor(s) due to a shadow cast by a second object in the detection area and/or if the second object obscures the first object or its shadow from view. This may occur, for example, when one or both of the first and second objects move during a pinching or dragging motion.